Scott Kelby, writing on Lightroom Killer Tips, has an article titled “Why I Don’t Convert My Raw Images To DNG”.
In my case, I’d mostly stopped converting raw images to DNG, after a short time of converting everything. However, I have been converting Sony images to DNG recently, mostly for the storage size benefits. I’m not worried about losing the ability to use first-party converters/editors, as I don’t use them in my workflow, but the lack of losslessly compressed raw files for Sony means that converting to DNG can be a big space saver, on the order of 20%. When you’re talking about hundreds of gigabytes, it can add up quickly, and there’s not really much of a downside from my perspective.